The present invention relates to a device for providing an electrical voltage using a battery system including a series connection consisting of a first battery submodule for providing a first battery submodule voltage and a second battery submodule for providing a second battery submodule voltage and with a first voltage conversion module for converting the first battery submodule voltage into an output voltage, which can be supplied to an electrical component that can be connected to the voltage conversion module. The invention additionally relates to a drive arrangement and a method.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Devices for providing an electrical voltage normally include an electrical energy store, which can for example be designed as a battery system. Such battery systems can be used to supply electrical loads, for example electrical machines, with energy. Such electrical machines can for example be arranged in motor vehicles and used to drive the motor vehicle. Electrical energy stores can however also be used as buffers for electrical energy. In this case electrical energy is provided by an electrical machine in generator mode and is buffered in the electrical energy store. Such electrical energy stores are known from wind turbines, for example.
One or more electrical loads can be connected to the battery system, and are supplied with electrical energy by the battery system. Since the voltage provided by the battery system is not equally suitable for all electrical loads, the electrical energy is normally transmitted from the battery system to the electrical load or loads via one or more voltage transformers.
A circuit arrangement according to the prior art is illustrated in FIG. 1. Here a battery system 10 with an internal resistance RI is electrically connected to a series connection on voltage conversion modules 20 via a supply line which has a parasitic inductances LI. An electrical load or an electrical component 30 is connected respectively to each of the voltage conversion modules 20.
The battery system 10 provides a battery system voltage US which is provided to the voltage conversion modules 20 via an inductance L. The battery system voltage US is split between the voltage conversion modules 20 such that a partial voltage UT of the battery system voltage US drops at each of the voltage conversion modules 20. The respective partial voltage UT is a function of the number of connected voltage conversion modules 20 and is scaled by way of this number of voltage conversion modules 20. The partial voltage UT dropping at a voltage conversion module 20 is transformed by means of the voltage conversion module 20 into a voltage suitable for the electrical component 30.
Each of the voltage conversion modules 20 generally includes a step-up converter. Such a step-up converter 22 is illustrated in FIG. 2. The step-up converter 22 normally includes two switching elements S1 and S2, which can be designed as semiconductor switches, as well as a load capacitor C and a reactance coil L, also called a charging reactor. The step-up converter 22 is designed to convert the partial voltage UT dropping at the voltage conversion module 20 into a DC output voltage UA, which is larger in size than the partial voltage UT.
The disadvantage of the circuit arrangement according to FIG. 1 and thus according to the prior art is that the power output of each voltage conversion module 20 must be approximately equal. To this end the voltage conversion modules 20 electrically connected in series to one another, as well as their loads 30, are generally designed to be identical. In particular it is not possible to provide flexible power for an electrical component 30 connected to a voltage conversion module 20. Flexible power here means that for example for a defined period an increased voltage is present at one or more of the voltage conversion modules.
Another disadvantage is that the step-up converters 22 of the voltage conversion modules 20 are over-dimensioned for a peak power and thus for most operating points. The over-dimensioning calls for larger components which mostly also have a poorer efficiency in the remaining operating points. In addition, all semiconductor switches S1 and S2 of all step-up converters 22 are in principle mostly dimensioned such that they can compensate for the failure of at least one voltage conversion module 20. This over-dimensioning of the step-up converters 22 and of the semiconductor switches S1 and S2 increases the system costs and the space requirement, and impairs the overall efficiency of the system, above all in partial load operation.
It is the object of the present invention to implement a low-cost and efficient solution in order to supply electrical components flexibly with electrical energy.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide a low-cost and efficient solution in order to supply electrical components flexibly with electrical energy.